I have been trying this problem which is supposed to be solved using fenwick trees The data structure i used is a tree where all the leaves are the array and for every node the value is sum of values of children. So we can calculate sum of the array between indices i and j in log n time. But it is saying Wrong Answer. Please help. #include <iostream>

include <stdio.h>

include <cmath>

include <string>

include <vector>

define vi vector<int>

define pi pair<int,int>

define si stack<int>

typedef long long int ll; using namespace std;

vector<long long="" int=""> v(2097152,0);

ll sum (ll a,ll b) { ll res = 0; //cout<<a<<" "<<b<<endl; if (b == (a+1)) { return v[b]+v[a]; } while (a < b) {

    if (a%2 != 0)
    {
        res+=v[a];a++;}
    if(b%2 == 0){res+=v[b];b--;}
    if (a == b)break;
    a/=2;
    b/=2;
//  cout<<a<<" "<<b<<endl;
//  cout<<"REs "<<res<<endl;
}
res+=v[a];
return res;

} int main () {

ll n,q;
cin >>n>>q;
ll var;
for (ll i = 0;i <n;i++)
{

    scanf("%lld",&var);
//var = 1000;
    v[i+1048576]=var;
    ll w = (i+1048576)/2;
    while(w >= 1)
    {
        v[w]=v[2*w]+v[2*w+1];
        w/=2;
    }
}
for(ll z =1;z <= q;z++)
{
    char c;
    cin >>c;
    if (c == 'S')
    {
        ll i,j;
        cin>>i>>j;
        //cout<<i<<" "<<j<<endl;
        //for(int i =0;i<5;i++)cout<<v[1048576+i]<<" ";
        cout<<sum(1048576+i,1048576+j)<<endl;
    }
    if (c == 'G')
    {
        ll i,va;
        cin>>i>>va;
            v[i+1048576]+=va;
    ll w = (i+1048576)/2;
    while(w >= 1)
    {
        v[w]=v[2*w]+v[2*w+1];
        w/=2;
    }
    }
    if (c == 'T')
    {
        ll i,va;
        cin>>i>>va;
            v[i+1048576]-=va;
    ll w = (i+1048576)/2;
    while(w >= 1)
    {
        v[w]=v[2*w]+v[2*w+1];
        w/=2;
    }
    }

}

}